It depends what you want it for . if you want one for show, then the werksone might be perfect, but don't buy one expecting a reduction in lift, in fact it could be the opposite.

The flat bottomed RSRs have naca ducts smartly positioned to allow for certain ventilation.

 

Here is a link to some pictures of the Downforce CF rear diffuser for the 996TT. The price is $2,500.

http://downforce.biz/dumpster/porsche/

They also said they need a non-turbo 996 to use to make brackets for this diffuser. So if anyone wants to volunteer their car they will get a discount on one. You can call them at 714-288-1630 to discuss it with them.

 

I think that looks fugly

 

Major issue for track cars( presuming you mean intercooler temps?)-- only trial and ERROR will decide usability in turbo application. Alzen car had re-routed.situated air to intercoolers that is quite different to to anything that looks remotely like original.
Anything related to aerodynamics cannot be looked at in isolation-- this applies even more so to underbody.

 

I spoke with Werks1 several months ago when their ad came out in
Excellence mag. They said they only made parts for the 997.
I tried to explain all the 996's that would be interested in their products
with no avail. Maybe if they were flooded with requests they would consider
building some parts. Just a thought

 

hmm... not looking as good as the one made by werks for the 997Tt....

 

Will it really do anything performace wise?

 

Deans carbon designs had a bolt on rear diffuser for sale i saw at santana row, he may build a custom one off if you ask him, or just buy the ones he has already, I dont have a pic, but he may so here is his number:
925 240 8899. I believe it was like $ 200. Not really into diffusers but to each his own.

 

Horrible, makes the car look cheap.